1. Field of the Invention
Aspects of the present invention relate to a fuel composition for a fuel cell as well as a fuel cell using the same, and more particularly, to a fuel composition which increases catalyst activity to maximize the performance of a fuel cell as well as a fuel cell having excellent performance by using the fuel composition.
2. Description of the Related Art
In a direct methanol fuel cell, electrons, protons, and carbon monoxide are generated from methanol as shown in Reaction Formula 1 below through adsorption of the methanol onto an anode catalyst.CH3OH→CO+4H++4e−  <Reaction Formula 1>
Carbon monoxide generated in the above reaction adheres to the anode catalyst, thereby decreasing the active area where additional oxidation occurs in the anode catalyst. Hence, power output is decreased. To improve power output, an anode catalyst which accelerates the additional oxidation of carbon monoxide (CO), a mixture of methanol and an aqueous liquid electrolyte as a fuel can be used. When a catalyst or the mixture as a fuel is used, methanol reacts with water in the anode to generate carbon dioxide and hydrogen ions, as shown in Reaction Formula 2 below.CH3OH+H2O→6H++CO2+6e−  <Reaction Formula 2>
A solid polymer electrolyte membrane is used as an electrolyte membrane in a direct methanol fuel cell. Generally, a perfluorinated polymer, such as commercially available NAFION®, is used as the solid polymer electrolyte membrane
However, methanol diffuses through a solid polymer electrolyte membrane. Thus, much methanol evaporates without being used to generate a current. Also, when methanol penetrates the solid polymer electrolyte membrane and contacts a cathode catalyst, the methanol is directly oxidized in the cathode, generating heat instead of a current. Thus, only a small current can be generated. In addition, protons generated at an anode catalyst layer pass through the solid polymer electrolyte membrane, and hence, the protons cannot smoothly move to the cathode catalyst layer, further reducing the generation of current.
In a fuel cell using methanol or sodium borohydride (NaBH4) as fuel, methanol or NaBH4 is used to produce electrons and hydroxyl ions (OH−) both of which pass through an electrolyte membrane to increase the current. In such a fuel cell, a variety of chemicals such as sodium thiosulfate (Na2S2O3), disodium phosphonate (Na2HPO3), and sodium phosphinate (Na2HPO2) can be used to smoothly generate OH−. (U.S. Pat. No. 6,773,470).
However, the performance of a fuel cell prepared using such a mixture of chemicals is still not satisfactory.